right on
Carracer has it right.
It used to be the law, under Idaho Code Section 36-401, but thankfully that bs provision was deleted. The old code section read:
It is a misdemeanor for any person to hunt, trap, or fish for or take any wild animal, bird or fish of this state or have in his possession any uncased firearm while in the fields or forests of the state, without first having procured a license....
Now section 36-401 has a provision that states:
(g) Nothing contained herein shall be construed to prohibit citizens of the United States who are residents of the state of Idaho from carrying arms for the protection of life and property.
Sadly, the former Attorney General for Idaho, Jim Jones, once issued an opinion that old the provision was constitutional and was okay because it was only intended to punish people who hunted without licenses. Here's the link to the opinion:
http://www.ag.idaho.gov/publications/op-guide-cert/1986/OP86-05.pdf
Fish and Game officers, however, pounced on the language and hassled, cited and arrested folks who were hiking with a gun, or target shooting. As I recall, there was once another provision that stated that possessing an uncased firearm in the field was prima facie evidence that the person was hunting; I believe that one was also deleted by legislation, because I can't find it anymore.
This may be off-topic, but there's still a provision, which I believe would be tossed out in court if pressed, that says fish and game officers have the authority and duty to:
"Search, with or without a warrant , the tents, wagons, autos, boats, aircraft (private or chartered), campers, camp trailers, or other vehicles, camps, baggage or packs of any person in the state, when they shall have probable cause to believe such person has in his possession any unlawfully taken wildlife or any equipment or substances used to take such wildlife."
It's Idaho Code section 36-1303. I have a problem with the no warrant business - don't you?
So, in summary, carracer has it right - there is no requirement to get a hunting license if you're traipsing around the fields and forests (or deserts, for that matter) and are carrying a gun. You may get contacted by a fish & game officer, who'll ask what/where/if you're hunting, and if you have a license, and who may accuse you of hunting and threaten all manner of arrest and citation, but as long as you deny hunting and say you are carrying for protection or target shooting, you don't have to worry about being convicted of hunting without a license.